The IV-29 is an uncommon Russian-made single dot indicator, built around VFD hot cathode technology. Much like the neon filled IN-28, the IV-29 is designed to be used as a single pixel in large segmented and bitmapped displays. This tube has a diameter of 29mmm and is quite large for a pixel indicator; the IN-28 and IV-29 actually use identical diameter glass envelopes in their construction, allowing the two tubes to be intermixed to make multicolor displays. The tube's flying lead base is designed to be directly soldered into the target device; the mind recoils at the thought of replacing burned out bulbs in a large matrix display constructed of these.

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Soviet-made IV-29 single dot indicator, normal operation.

Never before has the humble lamp been lavished with such over-engineering.